Measuring instrument.



C. L. WATKINS. MEASURING INSTRUMENT.

APPLICATION FILED 11m. 25, 1913.

I Patented Jan. 4, 1916.

r owing to the fact CHARLES LVWATKINS, or RQCK'HALL; MAR LA MEASURING INSTRUMENT.

My present invention relates broadly'to measuring instruments and has particular reference to that class of .devices whereby the distance of a ship from any'known 'geo graphical point may be ascertained.

. A further object of the invention contemr.

plates the provision of suchfnieans as will make it possible to readily ascertain plotted distances on marine charts. Heretofore it has been necessary in deter.- mining the distance of geographical point to the port off-destination to use or employ a v p operating the dividers and placing one point upon the spot indicating the present location of'the ship and the other point upon the port of destination indicated on thechart.

and moving the dividers over'to the scale provided in connection with the chart, the distance to be traveled'can This operation quite often proves inaccurate that the dividers either slightly close. or open during their movement from one place to another, which slight variation renders the distance determined inaccurate. In determining the direction of travel a pair of parallel rules is employed,

which operation is also ineffective and often inaccurate by reason of the possibility of the rules moving or widening when slid or moved upon the chart, and it is to overcome the above and various other objectionable features that the present invention has been designed.

WVith the above and various other objects in view, my invention relates to'such details of construction and arrangement and combination of the several parts as will be hereinafter fully described ed out in the appended claim.

In describing my invention in detail reference will be had to the accompanying drawings wherein like characters denote like or corresponding parts throughout the several views, and in which v Figure 1 is a plan view of the device. Fig. 2 is a similar view looking at the reverse side. Fig. 3 is an edge view. Fig. 4 isan Specification of Letters Patent.

'a'ship from a known pair of dividers. By

be ascertained.

well as the distance enlarged detail'view, and Fig. 5 is an enlarged sectional view of the disk and its supporting-means.- I p Before 'proce'edingwith the description 'of the drawings Ic'wish to call particular ,attent-ion to the ffact that While I have evolved my invent on with particular references to the ascertaining of plotted'distances on ma-. it may be readily.

rine or nautical. charts, utilized in connection with plane tables or} similar instruments. I I

Thepreferred embodiment of myY-invention comprehendsitwo main elements,- a pro-.

' tractor disk and a graduated'protractor arm,

indicated in the drawings by the numerals 1 as amass; rarest- W S-i Patented "Jan. 451915; Application filed. January 25,1913. s'eri'aiimmam." l

and Q res'pectiVely. The ,diskfl is preferably made of. metal and: provided with 'radially extending graduation marks '3. These marks are lettered in a manner, similar to the radial marks of a compass. The disk is centrally perforated to receive a pivotpin & which is journaled therein and projectslaterally fromeachface of vthe disk.- -The protractor arm or rule 2 is pivoted centrally of the disk by means of the offset ears 5 which are centrallyperforated and mounted for rotation on the pivot pin 4. One of the par-7 allel edges of the protractor arm 2 is provided with a plurality of graduated marks,

and the oppositev edge. is disposed in such relation to the disk 1 as to extend radially from the axis of rotation thereof, the purpose of which will be closed. The pivot pin above mentioned is preferably tubular in construction, the interior of which isprovided with a pair of hereinafter fully distransversely extending wires '6,-'the intersection of which indicates the exactcenter of the disk. Theperiphery of the disk is provided with a series or plurality. of notches 7, indicating the variation or tion from the meridian line runningfrom the north to the south magnetic pole.

I As regards the method of utilizing my de-' I dlIQCtlOIl of travel as vice to ascertain the to be traveled before of lestination the device is first place upon present location of the ship. VVhenthus placed, and with the north and south degree of devia either the meridian line or. nearest littltlltle'lll'le upon the chart, to the graduating marks directlyin the line of the.

meridian,

uated edge of the protractor arm is in said disk is slid or moved longitudinally upon said line until the grad indicating the present location of the ship and the port of destination, in Whichevent the distance to be traveled can be readily ascertained, as the graduation marks upon the said protractor arm are such as to conform exactly with the scale of the chart to Which it is applied. The said arm is preferably composed of two sections hingedlv connected as each section being provided With the necessary graduation marks. Having determined the distance to be traveled, the direction of travel is quickly determined by the position of the protractor arm relative to the disk. The opposite edge of the protractor arm being parallel with the graduated edge, and in perfect alinement or in radial relation With the center of the disk, the direction to be traveled Will be indicated upon the said disk as is clearly illustrated in Fig. 1 of the drawings.

It Will be seen from the foregoing taken in connection With the accompanying drawalinement with the point ings that the construction and operation of tion are eliminated the device is simple in the extreme, that the objectionable features attending devices employed for this purpose at present are completely avoided and that time and calculato a great extent in the practicalapplication of the invention.

It is thought from the foregoing that the advantages and novel features of my invention will be readily comprehended.

I desire it to be understood that I may make slight changes in the construction and in the arrangement and combination of the several parts provided such changes fall Within the scope of the subjoined claim.

Having thus fully described my inven tion, What I claim-as new and desire to secure by Letters Patent, is

A device to be used in connection with marine charts for finding the course'and distance to be traveled by a vessel at sea consisting of a graduated protractor disk having an opening at its center, a tubular member fitting the opening to act as a sight tube and a pivot pin, a. movable sectional protractor arm bifurcated at one end to straddle the disk, the respective arm extensions formed by the bifurcation aforesaid being laterally oifset. and engageable With the respective tubular member terminals to dispose one edge of said arm radially relatively to the center of the disk, and means Within the tubular member to indicate the exact center of Said disk, as and. for the purpose set forth.

V 7 CHARLES L. /VATKIN S. l/Vitnesses:

HARRY CLARK, FRANK B; WHEAT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, 1). c. i 

